Process of distilling wood.



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No. 843,599. PATENTED PEB. 12, 1907. C. s. HAMMATT. PROCESS 0FDISTILLING WO0D.

' APPLICATION FILED JUNE l2. 1906.

Kfm. Kvm.

CLARENCE S. IIAMMATT, OE JACKSONVILLE, FLORIDA.

PROCESS OF DISTILLING WOOD.

Specification of Letters Patent.

Patented Feb; 12, 1 907.

Application led .Tune 12, 1906. Serial No. 321,879.

To fdl whom, it may concern:

Be it known that I, CLARENCE S. HAM- MATT, a citizen of the UnitedStates, residing at Jacksonville, in the county of Duval and State olFlorida, -have invented a certain new and useful Process of DistillingVood; and I do hereby declare the following to be a full, clear, andexact description of the same, such as will enable others skilled in theart to which it appertains to make and use the same.

This invention relates to processes of distilling wood, and consists ina method of differentially extracting naturalvolatile constituents ofthewood and pyrolytic products of the same by a series ofdistillation-s, each carried out under appropriate conditions by meansof circulating bodies of indifferent gases of regulated temperature andcomposition, all as more fully hereinafter setforth, matters of noveltybeing particularly pointed out in the appended claims.

'Ille coniferous Woods contain the valuable constituents which are foundin the gum-turpentine oozing forth in tapping the live trees in thecustomary manner but it has hitherto proved difficult to extractturpentine and rosin from the Wood by a simple, ready, and economicalmethod delivering these bodies in a commercially pure and commerciallysatisfactory form. Most of the methods heretofore proposed depend upondistillations in one form or another; but in such distillations forreasons hereinafter a pearing' it has proved impractical to avoit thepresence in the distilled product of decomposition products ofturpentine, of rosin, or of the Wood. Generally, indeed, destructivedistillation of of wood and extraction of the turpentine have beenperformed in one and .the same operation. 'l he wood-turpentine of thetrade, therefore, usually has an unpleasant smell, from which it isnearly impossible to free it. Neither has it properties exactly liket-hcse of the 'ordinary turpentine from gum-turpentine. In most ofnthese prior methods the Wood has been heated in mass. Under theseconditions it is difficult to heat it uniformly and to an exacttemperature. Both because of the low conductive power of Wood for heatand because thespeciiic heat of 'Water being very high the evolution ofsteam in the mass tends to chill it locally, heat does not permeate themass Well. In'the effort to obtain suicient heat in interior portionsother portionsv of the mass are invariably overheated, with theresult ofthe stated decomposition. Efforts have/been made to remedy this bydistillation in a current of steam, but this apart from the ex ense ofgenerating the steam is objectiona le for a number of reasons. One isthat it adds inordinately to the amount of condensate and another isthat it seems t-o exercisev a catalytic or other decomposing action uponthe rosin, forming resinoils, and it seems also to exercise a similardestructive action upon athe. turpentine. V

Further, invorder to secure a perfectlyeven temperature throughout amass of Wood it would be necessary to employ an amount of steam quiteimpossible in practice. Wood naturally contains an enormous amount ofWa'fter even when dry, and this Water, taken together with the amount ofsteam which would be necessary for such even heating throughout, wouldform an enormous quantity of liquid to be handled by theturpentinecondensers.

vIn the present invention evenness of heating is secured by the use ofrapidly-circulating masses of indifferent permanent gases of thecharacter hereinafter described, which are able to carry heat throughoutthe mass of wood to be treated Without burdening theturpentine'condensers with an inordinate bulk of condensate. Preferablythese circulating gas masses are used-in connection with thin travelinglayers of sawdust, small chips, or other connninuted form of woodpassing `through a zone of increasing heat, the gas being preferablytransmitted transversely to the traveling layer. Further, in order toavoid the formation of decomposition productsthe distillation is dividedinto a plurality of different stages, `each `performed under the mostappropriate conditions. The distillation of turpentine and other naturalvolatile products of the Woodis completelyseparated from the destructivedistillation, and' such turpentine distillation is also preferably splitup into a number of stages.

By using transverse gas-currents which each pass through the travelinglayer of sawdust at one point and are then immediately Vremoved from thestill, as is done in the preferred lform of this invention, theturp'entine evolved at any 'such point can suffer no delI rco -composition.- It does not travel forward Wood-gas, &c.

with the wood, as would be the case :ifnother than transverse currentswere used, and -so become overheated or otherwise changed. Its existencein the form of vapor is, in fact, but momentary. It is removed bythegascurrent at the moment and at the point of volatilization and can beimmediately condensed. Again, since the traveling layer of sawdust inpassing through the zone of increasing heat described is progressivelyin creasing in heat atfeach successive point the vapors evolved are ofvdlerent character.' Therefore by uslng a .successlon of transversegas-currents at -a number of successive points different products can belobtained by 'ru-nning each such gas-current through -a separatecondensing apparatus, or, desired, the condensates from a number of suchtrans; verse currents or vfrom all' of lthem may be united to secureparticular commercial grades of turpentine. It is obviousthat thedescribed method offers considerable leXin bility in pthe matter ofsecuring such grades. In this fractional turpentine distillation-destructive distillation or pyrolysis vis precluded by regulation ofthe conditions, and thus products drawn off from zones of comparativelylow temperature 'are of cou-rse free of pyrolytic decompositionproducts. 'Condensed products from such zones-inayeasily be obtained ofthe character of any desired grade of the commercial turpentine, being,in fact, merely the natural turpentine.

The several gas-currentsvafter leaving the wood and passing through lthe'condenser or condensers to be stripped `of their Icondensable load maybe returned to .-serve anew.

Preferably this is done by causing the gasto circulate 1n closedcircuits, though. fresh gasresinication and alteration of fthe turpe'n,`

tine, &c. It is very desirable that the 7gas- 3 current should containno free oxygen. In

using products of combustion,therefore,'they are preferably admiXed'with 'a little Acom.v bustible gas and heated. They may, for

stance, pass into a checker-Work chamber, where the free oxygen and the4combustible l ustible gas does' no harm. The combusti-I ble gas evolvedin the destructivedistillation:

of Wood is quite suitable 'for this pur ose.

Whatever the particular gas emp oyed,it`

as will react'on'eachother. l -Excessof-oornshould be Aheated before useto an appropril ate temperature. The mass -of cornrninuted wood, whichis preferably pine sawdust,4

should be contained in a heat-insulated still to aid in procuring eventemperatures. The

particular gas teinperature employed will.

depend on the particular wood and the rapidity of circulation enployedas Well as upon the grade ofthe product desired, and is best controlledby observation of the quantity and quality of product delivered at thecondensthe more vrapid the Work with the same speed l of circulation. f

After complete removal of the turpentine and other volatile constituentsof the natural `-Wood the Wood is ordinarily submitted t0destructive'distillation, though the process may Fbe stopped after suchremoval and the purified wood Aused for some purposes for which it iseminently suitable, such as the manufactue of gunpowder,blasting-powder, as an absorbent for nitroglyeerin, as a fuel, &c.

In conducting destructive distillation .the jwood is also referablytreated in a current of hot `neutra gas. may be here used also; but the`permanent 6gases evolved in the distillation itself are like-Wise-suitable. The evolved distillation products are passed through acondenser in 'the ordinary manner and the acetic acid, methyl `alcohol,tar, &c., separated out, as usual, ands a-smallfraction 'of the gasesreheated and led backthrough :the charring wood.

In the Jaccompanying more or less diagrammatic illustration I 'haveshown one type of apparatus of the `many adapted to perform my process.

-In this illustration, Figure 1 is la view, 'partlyin vertical sectionVand partly -inelevation,'of a complete apparatus. Fig. 2 is la Asimilarview of -a modified detail of Fig. 1, and Fig. 3 is an enlarged detailview of the cones in Fig. co1.

In Fig. '1, 1 indicates as a whole the por- ICO Products of combustion=tiondf theapparatus designed for destruc- ,i or 'the sake Aof brevity,the destructive `still. 2 =indicates as a Whole the portion of theapparatus 'intended for regaining valuable vnaturalconstituents of theWood, which 'mpi be similarlyu called 'the ",turpentinest' A Theturpelftine-still comprises an' upright t-vf distillation of wood,h'ereinaftercalled,

shaft or column, which may be of any suitthe cone and through the layerof sawdust able material, but is here shown as constructsliding down thesame, through the'gas-outed of sheet-iron. However, since no heat letpipe, and thence through the condenser, transmission through its wallsis necessary or i seal-pot, and fan back into the conduit, cirdesirableit may be made of any other mateculating in closed circuit. -As thesawdust rial-such, for instance, as brickwork, terradescending betweenthe deliectors and the cotta, &c. Made of iron, as shown, it is preflnext adjacent portionl of the gas-conduit erably surrounded by aheating-casing 3, proforms a layer completely filling the opening videdwith a valved outlet-pipe 4, whichl, therebetween, there is no tendencyfor the when combustible gas is used as a heating gas flowing out of thegas-conduit intoa secagent may be supplied with a burner 5. tion of thestill to rise into the next upper Feed-inlet 6 serves for theintroduction of section or descend into the next lower. By raw material,usually with this apparatus this sim le means each section of the stillpine sawdust, chips from a sawmill-hog, practica ly forms anindependentstill,and,as &c. lnt-eriorly in its upper portion the shaft in the uppersections a drying actiont-akes is provided with an ordinary feed-screw7, place, due to the expulsion of water, there is serving to force thesawdust downward. Bea progressive increase in heat from the upper lowthis screw the wa'll of the shaft is proto the lower sections, using thesame body of vided with a number of annular deliectmghoods S, arrangedat intervals. Rising in the center of the shaft is a gas-conduit 9,provided with a number of conical-topped enlargements 10, provided withfine perforations 11 on their upper surfaces. The uppermost of thesecones 12 is not perforated and is made with a depending portion 12,forming a slip-joint in the top of the gas-conduit, which itsclfispreferably made of a number of sections with slip-joints. Seated on across-bar 13 in the gas-conduit is a springcontrolled pin adapted toforce said cone upwardly against the topmost deflector 8 and close andseal the opening 14, as shown in dotted lines.y It is obvious that withthis structure the size of the opening will adjust itself to the amountof sawdust descending. The sawdust thereby forms a seal against ascentof gas or vapors. Opening under each of the del'lectors is anoutlet-pipe 15, the deduit; but since the rate of increase is aptto besomewhat great fit is preferablel to use a valved auxiliary pipe 29,opening into the upper part of the gas-conduit to supplement the heat ofthe gases rising through theconduit. In the first section the absorptionof heat is inordinately great, since it is here that the bulk ofthewater leaves the wood. The sawdust is preferably well dried beforeentering; but it will still contain much water.

The gas-inlet pipe to the lower sections is a valved rosin-pipe 30,leading downwardto a seal-pot. (Not shown.) Any rosinwhich enters theperforations in the cones will `flow downward .into this rosinpipe.Special openings may be provided in the conduit for rosin-inlets.

Below the base of the gas-conduit is a pair of heated spirally-groovedgrinding-rolls Y31,

flectors serving to shield it against entrance set at an angle aneperforated to allow escape of sawdust. Each of these pipes is providedof gas. Very hot gas is fed into these rolls by with a depressedportion, opening from which is a valved pipe 16, leading ofi` to meansfor withdrawing condensates. (Not shown.) A water-pipe 17 provides for adrip of water on the whole series of these outletipes, thereby servingto condense vapors t rerein. Beyond the depression each of theoutlet-pipes is provided with a valve 18. By closing this the condensatefrom each section may be diverted separately and recovered, if desired.All the outlet-pipes, however, also communicate with a common down-pipe1 9, provided with a suction-fan 20 and condenser 21 and dependingthrough the top of a seal-tank 22. This tank is provided with aturpentine drawoff 23, a water-outlet 24, and a relief-pipe 25, whichmay be used to adjust pressures in the system. From the top of theseal-tank rises a valved gas-outlet pipe 26. This ipe communicates,through fan 27, with t e-central gas-conduit by means of pipe 28,passing through the wall of the shaft. It will be seen that by thisstructure gas is passed into the gas-conduit, out through theperforations of pipe 66 and serves to v olatilize rosin as such to agreat extent, the gas-current being very rapid, and therefore acting asan efficient eistilling agent for this purpose. Whatever rosin androsin-oils escape here are condensed and separately recovered from thelowernrost vaporoutlet 15. By lnclming the rolls melted rosin squeezed'out of the wood and not distilled fiows alongthem and dropsy on theperforated receiver 32, flowing thence into the resin-pipe 30.Preferably the tern- 4perature of the gas fed into this lower or rosincausing destructive distillation of the wood, as would be shown bycondensation of tarry products. From the bottom of the turpentine-stilldepends a coned and gated outlet 33, deliver- 34 of the destructivestill.

of superimposed` cylinrrical chambers 35,

. provided with a screw conveyer The hot gas to feed the vbottom of thegas-'conprovided with a depressed portion tapped by ICOv Section ofthestill is as hot as may be without izo ing treated Wood into thereceiving-hopper-12 5 The destructive still consists of a 'numbercommunicating at alternate ends and each 13o treated wood is forcedthrough these chambers and finally leaves the last as charcoal throughthe coned delivery 37, which acts as a gas-seal. Appropriate drivemachinery 38 serves to rotate the screw conveyers.

At or near the charcoal-delivery end is .a gas-inlet pipe 39. Gasintroduced into this flows successively through the chambersagainst theforward travel of the wood and finally exits through a come and pipe 40.This latter pipe passes through a Aconcenser 41 and thence downward intoa seal-pot 42, wherein concensed bocies accumulate ani are drawn offfrom time to time through valved pipes 43 and 44, acconing to theirspecific gravity. From vthe top of this sealpot leans a main gas-pipe 45for carrying oif the combustible incon\ ensable gases fermaL indestructive distillation. Fan 46 serves to maintain flow. Beyond the fanis a valve-.i pipe 47, tapping the main gas-pipe and provided with abranchpipe 48,en. ing in a gasjet under the gas-inlet pipe of theturpentinestill and serving to furnish heat to the same. Another valvedbranch 49 taps the said inletpi e and serves to replenish the gastherein W en circulating gas masses of the still are' composed ofcombustible gas from the (..estructive distillation. Another valved pipe50 taps the main gas-pipe and (felivers conibustible gas into thedestructive still through its inlet-pipe 39. On the hither si` `e of thevalve 5l leads off a branch pipe' 52,encing in a gas-jet under sai-.iinlet-pipe 39, which serves to furnish heat to its contents.

From the inlet-line 28 of the turpentinestill f leads a gas-pipe 53,which enters the jacket of the said still and serves to furnish hot gasas a heating and heat-insulating means.

When the demand for the combustible gas of the destructive still isgreat enough to make it desirable to economize in it or where anatmosphere of'dii'erent composition is desired for various chemicalreasons, proaucts of combustion from chimneystack 54 may be used. Thesedepart therefrom through pipe 55 and enter a structure 56, builtgenerally like a regenerator and containing bricks or similar masses ofresistant and heat-storing material 57. These serve to make uniform thetemperature of the products of combustion.` As such products, however,`generally contain an excess of free oxygen and as this `oxygen exercisesa detrimental effect where fine grades of turpentine are desired, thestructure shown is provided with a valved pipe 58, tapping the maingas-pipe and deliv-- ering a small portion of combustible gas into there enerator-chamber 59. Here this mixes with t e products of combustionand in passing through the hot checker-work effectually serves to removefree-oxygen Any slight excess of combustible gas (roes no harm and isusually mslgmficant 1n amount. 'From the regenerator the products leavethrough pipeline 60, containing fan 61. A valved branch 62 leads fromthis into the gas-replenishing pipe 49 of the turpentine-still. Anothervalved branch 63 leans down to the gas-inlet 39 of the destructive stillbeyondthe valve in sai i inlet.

By the described piping systems it is seen that-either or both stillsmay be feu with purified procucts of combustion, with ordinary productsof combustion, or with combustible gas from the (..estructive still.Ordinary profucts of combustion-Ji. e., those with some oxygen-areordinarily not cesirable; but they may be use in some cases.

In Fig. 2. a section of the turpentine-still is shown in which all theelements are the same as in the structure of Fig. 1, save that thecentral gas-conduit is here shown asa rotating hollow screw 64, providedwith a flange 65 to retain sawdust in the helical pathway. The uppersurface of the screw-blade is perforated to permit feeding of hot gasthrough the descending sawdust. Down this helical pathway the sawdusttravels by gravity, the screw being kept in slow rotation upon lthebearing 67.

' Using the structure shown the treatment of the wood kis erformed intwo distinct stages, the volati e natural constituent of the wood beingfirst expelled and then the Wood subjected to pyrolytic or destructivedistillation.. The first stage is again subdivided into as many as thereare sections in the particular length of tur entine-stillused. Bothdistillations are pe ormed in the presence of circulating gas massescomposed of indifferent gas, these masses preferably circulating inclosed circuits. In the turpentine-still the wood is caused to progressforward in a relatively thin layer through a heated zone of increasingheat, and at various points it is subjected to the volatilizinginfluence of a transverse gas-current passed through it, immediatelyremoved, stripped of its eondensable constituents, reheated, and reused.The eirculation is kept relatively rapid, and thereby the volatilizingand heatmg effect of the current is raised to a maximum, and, as in thepreferred form of the invention the gas is free both from free oxygenand any great amount of water-vapor,there is no deleterious eflect onthe turpentine or'rosin. ,y The turpentine is in the vapor form but fora fraction of a second and cannot be damaged by overheating. Further,since it is condensed under exclusion of air it does not suffer damageby oxidation.

The rapid current of hot gases of exact temerature passed through thedestructive still furnish'es amost convenient and readymethod of heatingthe Wood without local overheating, rendering possible the production ofhigh- `grade distillation. products, and since such gases are preferablyfree from oxygen there is IOO IIO

no loss of such delicate bodies as acetone, methyl alcohol, &c. Therelative proportions of the dfl'erent constituents recovered from thedestructive still will vary with the particular gas mass used. Withthecombustible gas there is frequently a tendency to favor the formation ofacetic acid, while with products of combustion relatively more acetoneis formed.

The pressure maintained within either or both stills may be above,below, or at atmosphere, as desired. Preferably, however, it is at orslightly above atmosphericfpressure,l as this prevents inliltration.Reduced pressure promotes the evolution of turpentine and also aids inthe destructive distillation; but the same ell'ect may be gained byincreasing the rapit'lity of the circulating gas-current, as Aaturpentine-lfree gas current, for example, absorbs turpentine veryreadily and at low temperatures. The same is true in the resindistillation, where a very rapid hot current of imlill'ercnt gas carriesover much of the resin unchanged. 'lherosin condensed from thisdistillation, being freeof dirt and oxidation products, is of primequality. 1n rosin distillation the gas-current may be at a teinpcratureof about 200o centigrade with advantage.

The condensed products from the first two or three sections of' theturpentine-still contain most of the water oi' the Wood, but carry alsosome turpentineof good quality. It has,

however,frequently a woodysmell, the small amount of aromaticconstituent which gives pine-wood its odor being carried over with thewater. vThe turpentine from the next few sections is large in quantity'and good in quality. That from the `lowerniost sections, at the pointwhere thc'heat is raised to distil resin, usually contains someresin-oil; but the products from allthese sections can be united to orma good commercial grade of turpentine. For liner qualities it isadvisable to collect the distillates separately, uniting suchcondensatcs as mayl be desirable to secure a given grade.

The a paratus shown may be indefinitely modifiedi 1. The process of'recovering turpentine from coniferous Wood which consists in sweeping abody of heated non-oxidizing indifferent permanent gas, maintained at atemperature too low to cause destructive decomposition of wood or'turpentine, in a closed circuit over said Wood, to and through acondenser, through a reheater and b'ackinto'contact with the wood.

2. The process of recovering valuable products from Wood Which consistsin distilling wood in an atmosphere of indifferent non-oxidizingpermanent gas at a temperature too low to cause destructivedecomposition of natural constituents to remove such naturalconstituents, and in then destructively distilliag said wood. y

3. The process of recoveringvaluable products from wood which consistsin producing a thin traveling layer of such Wood progressively passingthrough a plurality of closed heating-chambers of progressively-increasing temperature and in each such chamber contacting with it a currentof gas circulating in a closed circuit, said closed circuit including acondenser. o l

4. The process of recovering volatile oils from wood Which consists insweeping a current of heated wood-gas `at a temperature too low to causedestructive decomposition o1 wood oroil, in a closed circuit over saidwood, to and through a condenser, through a reheater nd lhack intocontact With the wood.

5. The processof recovering volatile oils from Wood which consists inproducing a thin traveling layer of such Wood and passing transverselythrough such layer at a plurality of points gas-currents circulating inclosed circuits to and through a condenser each succeeding gas-currentbeing of a higher tcmperature, through a reheater and back through thewood.

6. The recess of recovering turpentine from Woo which consists intransversely passing through a thin traveling layer of Wood a pluralityof isolated gas-currents of dil1`erenttemperatures at diierent pointsalong its line of travel.

7. The process of recovering valuable products from wood which consistsin distilling ollnatural volatile constituents by means of a current ofheated non-oxidizing indiil'erent, permanent gas circulating past saidWood in closed circuit, and in then destructively distilling said wood.

8. The process of recovering valuable roducts from wood which consistsin distiling oil natural volatile constituents by means of arapid'current of heated nonoxidizing indiil'erent permanent gascirculating past said Wood in a closed circuit and in then destructivelydistilling said wood by a current of heated gas also circulating pastsaid Wood in closed circuit.

9. The process of fractionally recovering valuable constituents of woodwhich consists indistilling oil natural volatile constituents of saidWood by a cessive currents of 1ndiHerentgases, successively increasin`in heat, circulating past said, wood in cosed circuits, and. in then'destructively distilling said Wood by a heated current of indifferentas, also circulating past said Wood in close circuit.

10. The process of regaining turpentine and rosiniromv Wood whichconsists in stripping said Wood of turpentine by a current of catednon-oxidizing permanent indiilerentgas circulating past said Wood inclosed circuit, and in then transmitting past' said wood lurality ofisolated suc'- y another current of hotter non-oxidizing permanentindiiferentgas circulating in closed circuit, both said currents beingmaintained at a temperature too low to destructively decompose the wood.

11. The process of regaining rosin-from wood which consists intransmitting `past said wood a rapid current oheated indiii'erent gas ata temperature justbelow the desaid wood through a plurality of heatechambers' isolated from' each other, each suc' ceeding chamber being ata higher-tempers'i-A ture though at a temperature below thedecomposing-pointof said wood, and in' separate y collecting the vaporsevolved from such Wood in each chamber.

14. The .process of recovering valuable products from wood whichconsists in passing said wood through a plurality of heated isolatedchambers at tem erature belowthe decomposing-point of woo to strip saidwood of turpentine treating it in each such chamlss ber With a currentof indiilerent'gas, and in then pressing the heated wood to extractrosm.

15: The process of products from wood Whichconsists in passing Woodthrough 'a series of compartments having isolated inlets and outlets,whereby the wood itself substantially seals such inlets and outletsagainst gas-passage, in passing heated p gas through each compartmentseparately,

recovering valuabley gas from each compartment.

1,6. The process of recovering valuable products from coniferouswood'which conand separately collecting the- 'vapor-charged.:

sists in stri ping the same of turpentine with currents o heated inertgases, recovering rosin at a higher temperature by distillationWithinert gas-currents and by pressure, and in then destructivelydistilling the residual wood.

17. The process of yrecovering valuable' products romvwood whichconsists in transmitting said wood-in a moving layer'through a series ofheated zones of successively-1ncreasing temperature, stripping it of'volatileI natural constituents in each such zone by a current of inertgas of appropriate temperature, and in then transmitting'theso-treatedwood through a zone of su'liicient temper` ature to char it, removingproduced volatile bodies by another current of inert gasof ap* propriatetemperature.

18. The process of recovering valuable products from wood which consistsinl transniitting said Wood in a moving layer through a series of heatedzones of successivelyfiin' creasing temperature', strip ing it ofvolatile natural constituents in eac such zone by a current of inert gasoi -a propriate tem e1"- ature traveling in close condenser, andinthentransmittingthe sol treated Wood. through a zone of' sufficienttemperaturev to char it, removing produced volatile bodies by anothercurrent'of inert circuit tliroug a gas of appropriatetemperaturetraveling in closed circuit through a condenser;

In testimonv whereof I atlix rny` signaturef in the presence of twowitnesses. CLARENCE S. HAMMA'IT.

Witnesses:

H. M. MARBLE, K. P. MQELROY.

